Test frequency selection for overdetermined system of fault equations

The paper deals with a multifrequency parametric fault diagnosis of linear analog circuits. The method can estimate the actual values of some network parameters. The components whose parameters are outside allowed tolerance intervals are classified as faulty. The parameter estimation process based on square system of equations uses measurements at several test frequencies while the rest of the frequency band may not be taken into account. An overdetermined system of fault equations can significantly reduce the error of solution. However, basic methods for test frequency selection usually find test frequencies which are distributed very close to each other which is not optimal in terms of an overdetermined system. For this reason, a new control mechanism based on a penalty function, which gives more regularly distributed test frequencies over the whole frequency band, is described in this paper. The proposed procedure is demonstrated on a test frequency selection for an EMI filter.